Gentlemen;
Sheet rocked the house last year. Where I painted with a light beige paint you can see some sheet rock screw outlines. They have not come thru the mud or protruded, but you can see black dots the size of the screw head? Mostly on the ouside walls. It looks like the black finish is staining the mud and it is showing thru the paint. Really no stains showing but just a black dot when you look at an angle. Anybody know why? The mud was typical 5 gal. Home Depot stuff. The wall was painted with a quality sheet rock primer and then a coat of Sherwin Williams semi gloss acrylic latex. The walls built of 2×4’s with fiberglass insulation with poly over , then sheetrock. A friend says its because I use wood heat. I have a hard time believing that! But who knows.
Replies
It is dust sticking to the condensation on the screw head sometimes you get mildew in bathrooms. Unless you can figure a way to get a thermal break I don't know how to get rid of it.The studs are transmitting the cold to the screw
With the info given, I'm gonna agree with the previous post. It's likely the cooler head of that screw causing the problem.
Wood heat in and of itself shouldn't necessarily put any particles in the air to collect on these screw heads, but if you're using a Fisher or potbelly type stove then you're opening the door and allowing particles to escape into the room. Or if your heat exchanger isn't dead tight on a unit connected to forced air circulation, some sooty materials could leak into the house. CO dangers could also result.
Do you burn candles in the house? Those are a good source of sooty material. Basically, the cheaper the candle, the more the soot.
If you're using a wood burning fireplace..........another potential source.
You could try washing the walls with some TSP or even Mr. Clean, then rinse well. If the spots diminish or disappear, you should then have the answer.
Knowledge is power, but only if applied in a timely fashion.
Edited 3/15/2005 10:52 pm ET by GOLDHILLER
Edited 3/15/2005 10:56 pm ET by GOLDHILLER
Both these guys are right on. It's the condensation on the cold screw catching any impurities in the air (that's one of the biggest giveaways in houses that have indoor air quality problems). In a normal home with naturally aspirating appliances the discolored screw heads would be more worrisome because the soot is just the harmless albeit ugly sign that many harmful substances are being drawn into your home. Which brings up a good point, even though your impurities may be less harmful than those from a gas appliance, you probably still want to fix it right?
The only way to stop it is to have a depressurized home. If you have even 5 Pascal of negative pressure (this is what happens when you turn on a bathroom fan in a tight house) you will be sucking air from the place with least resistance ie; your hot water heater exhaust, your leaky wood stove etc. You need to install a good ventilation system. Wether it's a full HRV system, or a simpler passive venting system where you have vents directly to outside air in every room, and a centralized fan(special bathroom fans can work) that is on an automatic switch. Ventilation is a very important part of modern building, not only for your paint job, but also for your health.
Edited 3/16/2005 2:24 am ET by sunny
Thanks guys, I can agree with the screws transmitting the cold. But there is no dust on the paint? Its like you held a black object behind a piece of white paper, you see the outline. Could it be the black oxide of the screw staining the mud. You can vaguely see the round spot of the head. None of the taped seams shows, just a few of the ones in the field. Appreciate all your opinions.
Hmmm... had a situation like that develop on a drywall job at a relatives many moons ago. It was nails rather than screws.
The nails had apparently been around a while... or some oil got into the box... or somehow... the oil got there (it was like used motor oil)... it will be one of life's mysteries how it got there.
We nailed the drywall up (this was before the screw-gun craze) and the nails stained the mud after the first coat. We couldn't get it sanded out. Baffled us for a long time... until my uncle went and got a nail from the box and looked at his hands.
We didn't even think twice about the messy hands we had after nailing that stuff up... too tired.
Long story short... my uncle made us take down all of that drywall. He said that the oil would leach into the mud forever if we didn't correct it.
Certainly don't KNOW that is your problem... but just another option.
Good luck in your quest.
>>> my uncle made us take down all of that drywall. He said that the oil would leach into the mud forever if we didn't correct it.
Too bad you had to do that. I would think an easier approach that's at least worth trying, and which has a good chance of working, is to paint the surface with a good quality sealer/primer (oil or shellac based, a couple coats over the trouble spots. ) That would keep the oil form leaching through.
I recently bought some drywall screws (10lb contractor plastic boxes) from the Depot, 2 boxes, these things were soaking wet in oil, a few tablespoons worth in the bottom of the box. it was a bitch getting that black greasy s##t all over my hands, the DW... WTF ??
It might... but you'd have had to have known my uncle to truly appreciate how infeasible that solution would have been to him!!
Partially disabled... but could do more with one good hand than 4 of us boys could do with 2 each! Machinist turned carpenter/do-everything guy. The ultimate perfectionist... and instilled that in all of us that used to work/learn with him. the guy used to sweat fit wood joints and see if he could get them to hold up... without splitting... and with no glue or fasteners whatsoever!
Do you really think he would have allowed us to paint primer over those spots? LOL
Now... for my advice... yes... try some kilz over the spot and wait about a month before repainting. If it is oil coming from the screw... it should show up within a month.. I think... maybe...
Black oxide won't migrate through the mud. It's not that diffusible. It's dirt sticking to the cold spot like the others said. The phenomenon is made worse by soot, as from candles, and from drywall screws that were longer than they needed to be.
Wayne; Shouldnt I be able to wash it off if it is dirt/soot etc?
I haven't had the problem in my house, so I never tried to wash it off. I'd think with the right detergent it should wash off.
I think you guys missed something he said:"Its like you held a black object behind a piece of white paper, you see the outline."Sounds to me like he's saying it's BELOW the surface rather then on it. So the dust/condensation thing can't be right.Could it be that the screws weren't countersunk and mudded over?
They're funny things, Accidents. You never have them until you're having them. [Eeyore]
Another thing to check is if the screw holes are slightly indented.
I've found that if I wipe a topping coat of light compound over the screw head and then do the final sanding before the topping has completely dried, that the head will be dished in...that is...not completely flat with the wall. And on a non-textured finished wall, this would be visible with a strong side-lite.
And I agree about the HD plastic box of screws being over-oiled. I had to wash my hands every so often to keep from putting ugly finger prints on the next sheet of drywall I put up.
BruceM
Boss; Your right, its behind the paint. They were indented and mudded and sanded several times, I took my time and used a couple fluorescent lights. I came out looking good and still does. Other than a few of the ones turning black behind the paint. The oil theory has me wondering. I think i still have a few leftover screws. Will check them out I f I can find one in an inconspicous spot I may scrape the paint off and see if the mud is stained or oiled or whatever is the culprit
If it's oil then probably a stain-killing primer would fix the problem.
Interesting.Your'e saying both the mud and the paint over these screws has become transparent/translucent?Oil just might do that.Knowledge is power, but only if applied in a timely fashion.
metal dust may be bleeding thru...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
Imbrxc; Is this common?
Imbrxc; Is this common?
could you elaborate a might more..
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
Could be plain old rust coming through.
spome of those screws are magnatized and you have finite paticle stuck to them...
place a rare earth magnet on them to try to demagnatize them...
be warned you ould make the problem worse..
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
I'm having this same thing happen in my home. The house was built back in the early 60's. It is showing up only on the outer perimeter walls, not the ones inside the house. We've been in the house for 20 years, I've painted the rooms maybe twice over that time frame, but last year I started noticing these dark dots at very regular intervals in vertical lines along the walls and even along the crown moulding. I'm sure it's nails and screws showing through or some sort of rust or stain bleeding through. You can't rub the spots off. It's ghosting right thru, staining the paint from underneath. One solution has been to paint the room a darker colour, but some rooms I don't want to be that dark. Would a good paint/primer combination do the trick? Should I paint something else over these areas first to prevent further bleed?
MLB, this repeats some of what you should have already read above.
Ghosting of studs in older less insulated homes usually suggests too high humidity in the winter months, often lasting past that season. Where are you located, what’s the interior humidity levels?
Causes that contribute would be smoking, many plants, fish tank and lots of pasta cooking. Damp crawl or basement is also a possibility.
That it is nail location might be showing the same results. A stain killing primer might solve the problem.....
Might not.
It's not the studs, it's the screws and nails. High humidity could be an issue. I'm in southern Ontario Canada where cold temps last from Nov - April. I haven't checked the humidity levels, but we do have a large 5 ft. high crawlspace under the front of the house (back-split). What's puzzling is that it's just been over the past 2 years they've shown bleed through and nothing, as far as we know, has changed. I'll try some stain killing primer. Thanks.
Yes, your nails not studs.
Is the crawl floor sealed and dry?
You’d be best served seeing if the humidity level is running over 30+%. Usually with a higher humidity level, even insulated glass window units will show condensation at the lower edges of the glass.
Same thing happened in the basement of my first home. We had a slight moisture problem due to improper basement finish of previous owner. I finished the basement properly and it took care of the issue. Have also seen it on some of my remodels. Mostly on exterior walls on homes built using plastic sheeting for vapor barrier (was a bad method). The moisture condenses on the screws b/c of extreme temp difference from out to inside of wall. Also, I notice a lot of rusted screws in these areas as well b/c of moisture issue. From my experience it’s always due to a moisture issue. Could be oily screws or something, but I would think the mud would not stick to a oily screw.
This is appearing in the ground level rooms over a finished basement/crawlspace. We had the basement professionally finished several years ago, but the crawlspace is unfinished. I agree, it is probably moisture issues. I'm just looking for a solution that doesn't involve refinishing the crawlspace or replacing the drywall/and screws. Thanks for your opinion!